Article ID: 326322 - View products that this article applies to.
This article was previously published under Q326322
Exchange Server uses the Internet Mail Service to communicate with other mail servers by means of Simple Mail Transfer Protocol (SMTP). When the Internet Mail Service receives an SMTP extended Hello (EHLO) protocol command from a connecting SMTP server, the Internet Mail Service responds by sending a status reply that starts with the following line:
250-Exchange_Server_IDHelloconnecting_server_IDIn that line:
Important Note that the attacker cannot simply send data to the Internet Mail Service to overrun the buffer. Instead, the attacker has to create a set of conditions that cause the Internet Mail Service to overrun its own buffer when it generates the EHLO response. Specifically, the attacker has to ensure that a reverse DNS lookup not only succeeds, but provides an FQDN with a length that is sufficient to cause the buffer overrun.
A supported hotfix is now available from Microsoft, but it is only intended to correct the problem that this article describes. Apply it only to systems that you determine are at risk of attack. Evaluate the computer's physical accessibility, network and Internet connectivity, and other factors to determine the degree of risk to the computer. See the associated Microsoft Security Bulletin
(http://www.microsoft.com/technet/security/bulletin/MS02-037.mspx)to help determine the degree of risk. This hotfix may receive additional testing. If the computer is sufficiently at risk, we recommend that you apply this hotfix now.
To resolve this problem immediately, download the hotfix by following the instructions later in this article or contact Microsoft Product Support Services to obtain the hotfix. For a complete list of Microsoft Product Support Services telephone numbers and information about support costs, visit the following Microsoft Web site:
http://support.microsoft.com/contactus/?ws=supportNote In special cases, charges that are ordinarily incurred for support calls may be canceled, if a Microsoft Support Professional determines that a specific update will resolve your problem. The usual support costs will apply to additional support questions and issues that do not qualify for the specific update in question.
Download InformationThe following file is available for download from the Microsoft Download Center:
Release Date: July 24, 2002
Download the Q326322 package now
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For additional information about how to download Microsoft Support files, click the following article number to view the article in the Microsoft Knowledge Base:
119591Microsoft scanned this file for viruses. Microsoft used the most current virus-detection software that was available on the date that the file was posted. The file is stored on security-enhanced servers that help to prevent any unauthorized changes to the file.
(http://support.microsoft.com/kb/119591/ )How to obtain Microsoft support files from online services
Installation InformationThis update supports the following switches:
File InformationThe English version of this hotfix has the file attributes (or later file attributes) that are listed in the following table. The dates and times for these files are listed in Coordinated Universal Time (UTC). When you view the file information, it is converted to local time. To find the difference between UTC and local time, use the Time Zone tab in the Date and Time tool in Control Panel.
Note Because of file dependencies, this update may contain additional files. This update requires Exchange Server 5.5 Service Pack 4.
Date Time Version Size File name and path -------------------------------------------------------------------------- 12-JUL-2002 12:58 5.5.2656.59 209,680 %EXSRVROOT%\Bin\Imcmsg.dll 12-JUL-2002 12:59 5.5.2656.59 503,568 %EXSRVROOT%\Connect\Msexcimc\Bin\Msexcimc.exe
Microsoft has confirmed that this problem may cause a degree of security vulnerability in the Microsoft products that are listed in the "Applies to" section.
For additional information about this vulnerability, visit the following Microsoft Web site:
Article ID: 326322 - Last Review: October 26, 2006 - Revision: 7.1